I bought two GP-635T. One always takes longer to get a fix but they work. My problem is that they both reside inside in my kitchen and coordinates fluctuate significantly up to a point where distance between them (calculated from appropriate formula…) varies from 20 to 500 meters, even after a while.

Next step of course is to test my stuff outside but any advice on stable position accuracy (batteries, 900mhz interferance,…)?

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